CaCO3 nanorods were synthesized via a facile solution route by polymer-controlled crystallization in the presence of polyacrylamide (PAM). The morphology, size and crystal structure were characterized by means of scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD). The results suggest that the as-synthesized product was CaCO3 (aragonite) nanorods with diameter ca. 50 nm and length ca. 1 mu m. Selected area electron diffraction (SAED) pattern shows the single-crystal nature of CaCO3 nanorods. The reaction time, temperature, pH and reactant concentration were systemically investigated. With the increase in the reaction time, hollow vaterite hexagonal disks can be obtained. (c) 2005 Elsevier B.V. All rights reserved.